The present invention pertains to means for using steam in internal combustion engines to provide better engine efficiency.
Gas turbines have some advantages in efficiency over other forms of internal combustion engines. Gas turbines use regenerators and intercoolers to take advantage of energy that would otherwise be lost as waste heat. Moreover, waste heat is gathered and expelled through the exhaust, leaving a high energy exhaust stream suitable for by-product power generation.
Conventional internal combustion engines, on the other hand, are only about 30% efficient--they only convert 30% of the energy put into them into work. Friction, turbulence, loss of heat to cylinder walls, incomplete combustion and many other effects combine to reduce efficiency. Conventional engines also generate a lot of heat and require means to irradiate heat. Moreover, conventional engines release nitrogen oxide pollutants through their exhaust.
The present invention adapts conventional internal combustion engines so that they will have many of the advantages of gas turbines.
An internal combustion engine operates by a series of energy conversions. The process begins with the chemical reaction between the oxygen in air and a combustible fuel. When the oxygen and fuel react in the combustion chamber of the engine, the chemical energy is converted to heat energy. The resulting heated gas expands and causes the piston to move, thus converting heat energy to mechanical energy.
Engines lose efficiency at each one of these conversions. Not all of the fuel combusts, and carbon monoxide and unburned hydrocarbons pass through the exhaust. The walls of the combustion chamber allow heat to escape, so that not all of the heat energy generated contributes to movement of the piston. Moreover, this escaping heat can be destructive, requiring a jacket coolant water supply. Jacket water, however, traps heat energy in unusable levels.
Various methods of increasing engine efficiency exist in the prior art. Prior art engine designs generally increase either the mass or temperature inside the combustion chamber to increase the pressure therein.
Steam injection is one method to increase engine efficiency existing in the prior art. Steam is a good, inexpensive, readily available medium to transfer heat and can absorb heat inside the combustion chamber. One can thus increase the total heat and pressure inside the combustion chamber by injecting steam into it. Various engine designs of the prior art use steam this way.
Supercharging and turbocharging are other methods of increasing engine efficiency. Supercharging generally refers to a compressor mechanically driven by the engine, while turbo-charging generally refers to a compressor driven by exhaust gases. Superchargers and turbochargers increase the heat energy produced in the combustion chamber by increasing the pressure of the air (and fuel in the case of a diesel engine) entering the combustion chamber, thus increasing the mass. Various existing engines use supercharging and turbocharging in this way.
The gains in efficiency of steam injection, turbocharging, and supercharging may be offset, however, if the engine has to burn more fuel to produce the steam or to charge the combustion chamber. Waste heat from the engine, however, may provide sufficient energy to produce the required steam. If a supply of water can absorb the engine's waste heat, so that at least a portion of the water boils, then the engine can produce steam without burning extra fuel. This steam, in turn, can be used in a steam compressor to produce the supercharging effect.
Presently, no method or structure exists for using a steam compressor in combination with an internal combustion engine. Steam injection, on the other hand, is known in the prior art. Some inventions also use waste heat to make steam for steam injection. Other inventions use turbochargers or water injection. None of these prior art inventions use waste heat steam to supercharge the engine.